UICollectionViewFlowLayoutestimatedItemSize 不能在 iOS12 上正常工作,尽管它在 iOS 11 上工作正常.* [英] UICollectionViewFlowLayout estimatedItemSize does not work properly with iOS12 though it works fine with iOS 11.*
问题描述
对于我们使用的 UICollectionView 的动态高度单元格,
For UICollectionView's dynamic height cells we use,
if let layout = self.collectionViewLayout as? UICollectionViewFlowLayout {
layout.estimatedItemSize = UICollectionViewFlowLayoutAutomaticSize
}
在高度和宽度的适当限制下,它适用于 iOS 11.* 版本,但它会中断并且不会使单元格在 iOS 12.0 中动态化
with the proper constraint of height and width, it works fine with iOS 11.* versions but it breaks and does not make the cells dynamic for iOS 12.0
推荐答案
在我的例子中,我通过向单元格的 contentView 显式添加以下约束来解决这个问题.
In my case, I solved this by explicitly adding the following constraints to the cell's contentView.
class Cell: UICollectionViewCell {
// ...
override func awakeFromNib() {
super.awakeFromNib()
// Addresses a separate issue and prevent auto layout warnings due to the temporary width constraint in the xib.
contentView.translatesAutoresizingMaskIntoConstraints = false
// Code below is needed to make the self-sizing cell work when building for iOS 12 from Xcode 10.0:
let leftConstraint = contentView.leftAnchor.constraint(equalTo: leftAnchor)
let rightConstraint = contentView.rightAnchor.constraint(equalTo: rightAnchor)
let topConstraint = contentView.topAnchor.constraint(equalTo: topAnchor)
let bottomConstraint = contentView.bottomAnchor.constraint(equalTo: bottomAnchor)
NSLayoutConstraint.activate([leftConstraint, rightConstraint, topConstraint, bottomConstraint])
}
}
这些约束已经存在于单元格的 xib 中,但不知何故,它们对于 iOS 12 来说还不够.
These constraints are already in place inside the xib of the cell, but somehow they aren't enough for iOS 12.
建议在各个地方调用 collectionView.collectionViewLayout.invalidateLayout()
的其他线程对我的情况没有帮助.
The other threads that suggested calling collectionView.collectionViewLayout.invalidateLayout()
in various places didn't help in my situation.
此处的示例代码:https://github.com/larrylegend/CollectionViewAutoSizingTest
This applies the workaround to code from a tutorial by https://medium.com/@wasinwiwongsak/uicollectionview-with-autosizing-cell-using-autolayout-in-ios-9-10-84ab5cdf35a2:
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